CA1220322A - Process for producing silicon tetrafluoride - Google Patents
Process for producing silicon tetrafluorideInfo
- Publication number
- CA1220322A CA1220322A CA000482735A CA482735A CA1220322A CA 1220322 A CA1220322 A CA 1220322A CA 000482735 A CA000482735 A CA 000482735A CA 482735 A CA482735 A CA 482735A CA 1220322 A CA1220322 A CA 1220322A
- Authority
- CA
- Canada
- Prior art keywords
- fluoride
- silicon tetrafluoride
- silicon
- fluorine
- acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B33/00—Discharging devices; Coke guides
- C10B33/08—Pushers, e.g. rams
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/08—Compounds containing halogen
- C01B33/107—Halogenated silanes
- C01B33/10705—Tetrafluoride
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/08—Compounds containing halogen
Abstract
Abstract A process for producing silicon tetrafluoride by hydrolysis of gases containing silicon fluoride, the hydrolysate being reacted with sodium fluoride, potassium fluoride and/or barium fluoride and the reaction product obtained decomposed thermally, thereby forming silicon tetrafluoride.
Description
~03~2 1 A Process for Producing Silicon Tetrafluoride .... .
The invention relates to a process for producing pure silicon tetrafluoride from gases containing silicon fluorine as obtained, for example, during the wet extraction of raw phosphates or when glass bodies are pickled with a mixture of hydroEluoric and sulfuric acids. These gases predominantly contain silicon tetrafluoride, but may also contain hexafluorosiloxane, fluorosilicic acids and hydrofluoric acid.
Silicon tetrafluoride (Sift) is used in a variety of ways.
For example, it is used for treating dried concrete parts in order to provide a considerable improvement of their waterproofness and resistance to corrosion and abrasion (G. Roederer, Communed. (Paris) 84, 912-924, 1960).
It is alto used to increase the hydrophobic character of crystalline molecular sieves.
It is used to produce highly dispersed silicic acid and hydrofluoric acid (US. patent no. 3,969,485, German Offenlegungsschrift 2132426, German OEfenlegungsschrift 2132428, German Offenlegungsschrift 2132429).
It is suitable for producing orthosilicic acid esters (Herman patent no. 2609767).
High-grade silicon can be obtained from it (German OffenlegungsschriEt 3206766, A. Sanjurjo et at, J.
ElectrochemO Sock 128 (1981) 179-184).
It is also suitable for obtaining amorphous silicon for photo-voltaic cells (cf. for example Makoto Congo en at Apply Pays. Let. JO (1980) 599 and A. Madman! S. R.
Ovation-I, 33~:
l sky, E. Bonn, Phil.Mag. B 40, 259 (1979)).
It is also used for obtaining Solon (D. K. Podium et at, J. Fluorine Chum. 1979, 14(4), 327-9, German patent no. 1034159, German patent no. 1080077, So patent no.
The invention relates to a process for producing pure silicon tetrafluoride from gases containing silicon fluorine as obtained, for example, during the wet extraction of raw phosphates or when glass bodies are pickled with a mixture of hydroEluoric and sulfuric acids. These gases predominantly contain silicon tetrafluoride, but may also contain hexafluorosiloxane, fluorosilicic acids and hydrofluoric acid.
Silicon tetrafluoride (Sift) is used in a variety of ways.
For example, it is used for treating dried concrete parts in order to provide a considerable improvement of their waterproofness and resistance to corrosion and abrasion (G. Roederer, Communed. (Paris) 84, 912-924, 1960).
It is alto used to increase the hydrophobic character of crystalline molecular sieves.
It is used to produce highly dispersed silicic acid and hydrofluoric acid (US. patent no. 3,969,485, German Offenlegungsschrift 2132426, German OEfenlegungsschrift 2132428, German Offenlegungsschrift 2132429).
It is suitable for producing orthosilicic acid esters (Herman patent no. 2609767).
High-grade silicon can be obtained from it (German OffenlegungsschriEt 3206766, A. Sanjurjo et at, J.
ElectrochemO Sock 128 (1981) 179-184).
It is also suitable for obtaining amorphous silicon for photo-voltaic cells (cf. for example Makoto Congo en at Apply Pays. Let. JO (1980) 599 and A. Madman! S. R.
Ovation-I, 33~:
l sky, E. Bonn, Phil.Mag. B 40, 259 (1979)).
It is also used for obtaining Solon (D. K. Podium et at, J. Fluorine Chum. 1979, 14(4), 327-9, German patent no. 1034159, German patent no. 1080077, So patent no.
2,933,37~)-It is also suitable as an etching medium for materials containing silicon in the semiconductor industry Us patent no.
4 262 409).
It is already known (Proc.-Fert.Soc. (PFRSAZ) V 163, 1977) lo to produce silicon tetrafluoride from waste gases which are obtained during the wet extraction of raw phosphates, by hydrolyzing the waste gases and, to dissolve precipitated silicic acid, converting them with waste gases containing hydrofluoric acid into an approximately 20~ hexafluo-silicic acid solution. This solution is decomposed at 100 to 110C in reactors made of nickel alloys with con-cent rated sulfuric acid to form silicon tetrafluoride which is volatile under these conditions. Hexafluorosilicic acid solution can be added until the concentration of sulfuric acid has decreased to 70 to 75%.
The application of this process is opposed by great probe lets involving the materials, in view of the corrosiveness of the acid mixtures at the necessary high reaction them-portray and the great amount of waste sulfuric acid formed, which is contaminated by fluorine compounds.
The problem on which the invention is based is to provide a process for producing pure silicon tetrafluoride without the simultaneous formation of byproducts which are hardly capable of being used.
1 The invention is based on the finding that this problem can be solved by converting a hydrolysate obtained by hydrolyzing gases containing sift-con fluorine, with sodium fluoride, potassium fluoride or barium fluoride, into single product being a corresponding alkali or alkaline earth hexafluosilicate, although the hydrolysate contains complex compounds. The hexafluorosilicate can then be processed further in a simple manner to form pure silicon tetrafluoride.
The object ox the invention is a process for producing sift-lo con tetrafluoride, which is characterized in that gases containing silicon fluorine are hydrolyzed, the hydrolysate is reacted with sodium fluoride, potassium fluoride or barium fluoride and the reaction product obtained is de-composed thermally, thereby forming silicon tetrafluoride.
It is particularly advantageous that the metal fluoride which is also formed during thermal decomposition can be recycled.
The inventive process may be illustrated with reference to the following equations.
F4 OWE -? Sophie + Sue (1) (4 -I x) H2S.iF6 (2~x)SiO2~aq ________ (pa) 6 HXSiF4*x (4 2X)H2 2 6 awoke ( 2) ~~~~~~~~~~ 12)
4 262 409).
It is already known (Proc.-Fert.Soc. (PFRSAZ) V 163, 1977) lo to produce silicon tetrafluoride from waste gases which are obtained during the wet extraction of raw phosphates, by hydrolyzing the waste gases and, to dissolve precipitated silicic acid, converting them with waste gases containing hydrofluoric acid into an approximately 20~ hexafluo-silicic acid solution. This solution is decomposed at 100 to 110C in reactors made of nickel alloys with con-cent rated sulfuric acid to form silicon tetrafluoride which is volatile under these conditions. Hexafluorosilicic acid solution can be added until the concentration of sulfuric acid has decreased to 70 to 75%.
The application of this process is opposed by great probe lets involving the materials, in view of the corrosiveness of the acid mixtures at the necessary high reaction them-portray and the great amount of waste sulfuric acid formed, which is contaminated by fluorine compounds.
The problem on which the invention is based is to provide a process for producing pure silicon tetrafluoride without the simultaneous formation of byproducts which are hardly capable of being used.
1 The invention is based on the finding that this problem can be solved by converting a hydrolysate obtained by hydrolyzing gases containing sift-con fluorine, with sodium fluoride, potassium fluoride or barium fluoride, into single product being a corresponding alkali or alkaline earth hexafluosilicate, although the hydrolysate contains complex compounds. The hexafluorosilicate can then be processed further in a simple manner to form pure silicon tetrafluoride.
The object ox the invention is a process for producing sift-lo con tetrafluoride, which is characterized in that gases containing silicon fluorine are hydrolyzed, the hydrolysate is reacted with sodium fluoride, potassium fluoride or barium fluoride and the reaction product obtained is de-composed thermally, thereby forming silicon tetrafluoride.
It is particularly advantageous that the metal fluoride which is also formed during thermal decomposition can be recycled.
The inventive process may be illustrated with reference to the following equations.
F4 OWE -? Sophie + Sue (1) (4 -I x) H2S.iF6 (2~x)SiO2~aq ________ (pa) 6 HXSiF4*x (4 2X)H2 2 6 awoke ( 2) ~~~~~~~~~~ 12)
3 M2SiF6 (EM Sift) + 2~2 3 M2SiF6 (EM Sift) I Sift + EM F (EM F2) (3) l MI = Nay K
MIX = Be x = 0.5 to 2 According to equation (1), the hydrolysis takes place with water. The system hexafluorosilicic acid (H2SiF6) and hydrate Ed silicic acid (Sue a) is in equilibrium with moo-nuclear complexes of the general formula HXSiF4+x, wherein x attains values of approximately 0.5 to a maximum of 2 as a function of the total concentration of hexafluorosilicic lo acid. Thus, x = 1.1 for 30~ Sophie, for example (cf.
Ullmann Thea edition Vol. 11 p.61~). It is as yet unclear at present, however, to what extent other ligands than F, such as OH or OH, are coordinated to the mononuclear come plexus.
It has now been found that the equilibrium shifts completely to the side of the corresponding he~afluorosilicates when this suspension of silicic acid gel in fluorosilicic acids is stirred with sodium fluoride, potassium fluoride or be I'm fluoride, the he~afluorosilicates being precipitated as difficultly soluble compounds. The fluorides are preferably used in stoichiometric amounts according to equation (2).
A single defined silicon fluorine compound forms with the hexafluosilicate. The hexafluosilicate is separated, dried and then decomposed thermally, whereby pure silicon twitter-fluoride is obtained and the metal fluoride used is recovered and may be returned to the process.
The performance of the process shall be explained in more detail with reference to the flow sheet shown in the drawing.
The gas containing silicon fluorine is hydrolyzed with water 1 in a waste gas scrubber. The provenance of the gas con-twining silicon fluorine is in principle irrelevant.
The Sophie ratio of the gases should preferably be be-tweet 1/4 and 1/5, so that the concentration of hydra-fluoric acid in the hydrolysate does not increase too much. In waste gases of acid polishing, in which glass bodies are pickled with a mixture of hydrofluoric and sulfuric acids, the fluorine content may reach values of up to 50g/Nm3, possibly up to 100g/Nm3; the Sophie ratio is in the desired range. In apparatus for the wet extraction of raw phosphates, the fluorine content in the waste gas depends upon the quality of raw phosphate used.
About 20 g fluorine/Nm3 may be stated as a standard value.
The silicon content is frequently less than 1/4 or 1/5 the amount of fluorine in gram atoms, also depending on the quality of raw phosphate used. Material containing quartz or silicic acid is then expediently added to the reaction material.
The inventive process may be applied with qualities of silicon tetrafluoride of any concentration, and may thus be applied as a "purification process" at high concentrations.
The hydrolysate obtained is vigorously stirred preferably for 1/2 to hours in corrosion-resistant agitator vessels with the stoichiometric amount of metal fluoride which comes out of the reactor for thermally decomposing hex-fluorosilicate. The metal fluoride may be used in powder form, in solution or - particularly advantageously - as a suspension. The hexafluosilicate obtained in the ago-talon vessel is separated and dried. The filtrate forming during separation and the waste air obtained during drying may be fed back into the waste gas scrubber. In the process, hexaEluorosilicate yields of over 90~ are ox-twined when sodium fluoride and potassium fluoride are used, and yields of about 85~ when barium fluoride is used, 3~:2 1 in each case with respect to the metal fluoride used.
The purity of the alkali h~xafluorosilicates which may be obtained is greater than 99%, that of the barium hexafluorosili-gate about 90%. The alkali hexafluorosilicates are Essex-tidally contaminated by silicic acid and water, the bariumhexafluorosilicate additionally by barium fluoride, above all.
The dried hexafluorosilicates are decomposed thermally to form silicon tetrafluoride and metal fluoride, maintaining a corresponding underpricer. This pressure is maintained lo by pumping out the silicon tetrafluoride as it is obtained.
The following decomposition conditions have proved useful:
for Na2SiF6 100 mar at 600C
for K2siF6 100 mar at 550C
for BaSiF6 100 mar at 500C
Conditions of 0.1 to 500 mar and 400 to 800C may generally be used. The silicon tetrafluoride obtained has at least a purity greater than 90 vowel, preferably 95 vol.% and in particular greater than 99 vowel. The purity of the silicon tetrafluoride obtained depends essentially on the leakage rate of the decomposition apparatus, whereby qualities of Sift with a purity greater than 99 vol.% may easily be attained. The contamination is essentially air and traces of hexafluosiloxane, hydrofluoric acid and sulfuric dioxide.
The metal fluoride obtained during the thermal decomposition is fed back into the process and added in doses to the hydra-Lucite of waste gases containing silicon fluorine in the agitator vessel.
The particular advantages of the inventive process lie in its economy and ecological value. The process is economical because it proceeds from virtually worthless waste gas scrubber liquids which form in very large amounts and must not by any means be let into the outfall ditches, for equal-jackal reasons.
~20322 1 The whole process can be purify with apparatus which is in principle known and tested industrially. No reactors of expensive non-ferric alloys are necessary.
The process is ecologically useful because it allows for pure silicon tetrafluorideto be obtained from waste gases, all necessary adjutants being conducted in a cyclic process.
No substances which need to be disposed of are formed, which is particularly advantageous in view of the physic-logical effectiveness of fluorine compounds.
The invention shall be explained in more detail by the following example.
Exam Waste gases from an acid polishing unit in which glass bodies are pickled with a mixture of hydrofluoric and sulfuric acids, were hydrolyzed in a centrifugal scrubber.
800 1 of this hydrolysate, a suspension of gelatinous silicic acid in fluorosilicic acids with a total content of 94.68 g F/l and 33.34 g Sill, were transferred to an agitator vessel, mixed with 80 kg ground sodium fluoride, vigorously stirred for 2 hours and filtered off. The filtrate was conducted back into the waste gas scrubber and the filter cake put through a fluid bed drying Papa-fetus. 169 I sodium hexafluosilicate in powder form was obtained at a yield of 94% of the theory with respect to the sodium fluoride used, and with a content of 99.5~ sodium hexafluosilicate. The waste air from the drying apparatus was conducted into the centrifugal scrubber. 40 kg of the sodium hexafluorosilicate obtained were filled into a non-scaling steel drum and decomposed thermally to form sodium fluoride and Sift in the course of 2 hours at 620QC and a pressure less than 200 mar, maintained by pumping out.
, 1 21.7 kg Sift were obtained, i.e. 98% of the theory with no-spent to the sodium hexafluosilicate used, with a content of 99 vol.%. The following impurities were found:
air: 0.6 vol.%
Sophie 0.2 vol.%
S2 <0.005 vol.%
MIX = Be x = 0.5 to 2 According to equation (1), the hydrolysis takes place with water. The system hexafluorosilicic acid (H2SiF6) and hydrate Ed silicic acid (Sue a) is in equilibrium with moo-nuclear complexes of the general formula HXSiF4+x, wherein x attains values of approximately 0.5 to a maximum of 2 as a function of the total concentration of hexafluorosilicic lo acid. Thus, x = 1.1 for 30~ Sophie, for example (cf.
Ullmann Thea edition Vol. 11 p.61~). It is as yet unclear at present, however, to what extent other ligands than F, such as OH or OH, are coordinated to the mononuclear come plexus.
It has now been found that the equilibrium shifts completely to the side of the corresponding he~afluorosilicates when this suspension of silicic acid gel in fluorosilicic acids is stirred with sodium fluoride, potassium fluoride or be I'm fluoride, the he~afluorosilicates being precipitated as difficultly soluble compounds. The fluorides are preferably used in stoichiometric amounts according to equation (2).
A single defined silicon fluorine compound forms with the hexafluosilicate. The hexafluosilicate is separated, dried and then decomposed thermally, whereby pure silicon twitter-fluoride is obtained and the metal fluoride used is recovered and may be returned to the process.
The performance of the process shall be explained in more detail with reference to the flow sheet shown in the drawing.
The gas containing silicon fluorine is hydrolyzed with water 1 in a waste gas scrubber. The provenance of the gas con-twining silicon fluorine is in principle irrelevant.
The Sophie ratio of the gases should preferably be be-tweet 1/4 and 1/5, so that the concentration of hydra-fluoric acid in the hydrolysate does not increase too much. In waste gases of acid polishing, in which glass bodies are pickled with a mixture of hydrofluoric and sulfuric acids, the fluorine content may reach values of up to 50g/Nm3, possibly up to 100g/Nm3; the Sophie ratio is in the desired range. In apparatus for the wet extraction of raw phosphates, the fluorine content in the waste gas depends upon the quality of raw phosphate used.
About 20 g fluorine/Nm3 may be stated as a standard value.
The silicon content is frequently less than 1/4 or 1/5 the amount of fluorine in gram atoms, also depending on the quality of raw phosphate used. Material containing quartz or silicic acid is then expediently added to the reaction material.
The inventive process may be applied with qualities of silicon tetrafluoride of any concentration, and may thus be applied as a "purification process" at high concentrations.
The hydrolysate obtained is vigorously stirred preferably for 1/2 to hours in corrosion-resistant agitator vessels with the stoichiometric amount of metal fluoride which comes out of the reactor for thermally decomposing hex-fluorosilicate. The metal fluoride may be used in powder form, in solution or - particularly advantageously - as a suspension. The hexafluosilicate obtained in the ago-talon vessel is separated and dried. The filtrate forming during separation and the waste air obtained during drying may be fed back into the waste gas scrubber. In the process, hexaEluorosilicate yields of over 90~ are ox-twined when sodium fluoride and potassium fluoride are used, and yields of about 85~ when barium fluoride is used, 3~:2 1 in each case with respect to the metal fluoride used.
The purity of the alkali h~xafluorosilicates which may be obtained is greater than 99%, that of the barium hexafluorosili-gate about 90%. The alkali hexafluorosilicates are Essex-tidally contaminated by silicic acid and water, the bariumhexafluorosilicate additionally by barium fluoride, above all.
The dried hexafluorosilicates are decomposed thermally to form silicon tetrafluoride and metal fluoride, maintaining a corresponding underpricer. This pressure is maintained lo by pumping out the silicon tetrafluoride as it is obtained.
The following decomposition conditions have proved useful:
for Na2SiF6 100 mar at 600C
for K2siF6 100 mar at 550C
for BaSiF6 100 mar at 500C
Conditions of 0.1 to 500 mar and 400 to 800C may generally be used. The silicon tetrafluoride obtained has at least a purity greater than 90 vowel, preferably 95 vol.% and in particular greater than 99 vowel. The purity of the silicon tetrafluoride obtained depends essentially on the leakage rate of the decomposition apparatus, whereby qualities of Sift with a purity greater than 99 vol.% may easily be attained. The contamination is essentially air and traces of hexafluosiloxane, hydrofluoric acid and sulfuric dioxide.
The metal fluoride obtained during the thermal decomposition is fed back into the process and added in doses to the hydra-Lucite of waste gases containing silicon fluorine in the agitator vessel.
The particular advantages of the inventive process lie in its economy and ecological value. The process is economical because it proceeds from virtually worthless waste gas scrubber liquids which form in very large amounts and must not by any means be let into the outfall ditches, for equal-jackal reasons.
~20322 1 The whole process can be purify with apparatus which is in principle known and tested industrially. No reactors of expensive non-ferric alloys are necessary.
The process is ecologically useful because it allows for pure silicon tetrafluorideto be obtained from waste gases, all necessary adjutants being conducted in a cyclic process.
No substances which need to be disposed of are formed, which is particularly advantageous in view of the physic-logical effectiveness of fluorine compounds.
The invention shall be explained in more detail by the following example.
Exam Waste gases from an acid polishing unit in which glass bodies are pickled with a mixture of hydrofluoric and sulfuric acids, were hydrolyzed in a centrifugal scrubber.
800 1 of this hydrolysate, a suspension of gelatinous silicic acid in fluorosilicic acids with a total content of 94.68 g F/l and 33.34 g Sill, were transferred to an agitator vessel, mixed with 80 kg ground sodium fluoride, vigorously stirred for 2 hours and filtered off. The filtrate was conducted back into the waste gas scrubber and the filter cake put through a fluid bed drying Papa-fetus. 169 I sodium hexafluosilicate in powder form was obtained at a yield of 94% of the theory with respect to the sodium fluoride used, and with a content of 99.5~ sodium hexafluosilicate. The waste air from the drying apparatus was conducted into the centrifugal scrubber. 40 kg of the sodium hexafluorosilicate obtained were filled into a non-scaling steel drum and decomposed thermally to form sodium fluoride and Sift in the course of 2 hours at 620QC and a pressure less than 200 mar, maintained by pumping out.
, 1 21.7 kg Sift were obtained, i.e. 98% of the theory with no-spent to the sodium hexafluosilicate used, with a content of 99 vol.%. The following impurities were found:
air: 0.6 vol.%
Sophie 0.2 vol.%
S2 <0.005 vol.%
Claims (2)
1. A process for producing silicon tetrafluoride, characterized in that gases containing silicon fluorine are hydrolyzed, the hydrolysate reacted with sodium fluoride, potassium fluoride or barium fluoride, and the reaction product obtained decomposed thermally, thereby forming the silicon tetrafluoride.
2. The process according to claim 1, characterized in that the metal fluoride which forms during thermal decomposition is recycled.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3432678A DE3432678C2 (en) | 1984-09-05 | 1984-09-05 | Process for the production of silicon tetrafluoride |
| DEP3432678.2-41 | 1984-09-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1220322A true CA1220322A (en) | 1987-04-14 |
Family
ID=6244730
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000482735A Expired CA1220322A (en) | 1984-09-05 | 1985-05-29 | Process for producing silicon tetrafluoride |
Country Status (12)
| Country | Link |
|---|---|
| US (1) | US4615872A (en) |
| EP (1) | EP0173793A3 (en) |
| JP (1) | JPS6168315A (en) |
| KR (1) | KR860002419A (en) |
| CA (1) | CA1220322A (en) |
| DD (1) | DD236511A5 (en) |
| DE (1) | DE3432678C2 (en) |
| DK (1) | DK133585A (en) |
| ES (1) | ES8606828A1 (en) |
| FI (1) | FI75330C (en) |
| IN (1) | IN162367B (en) |
| NO (1) | NO851213L (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8614539D0 (en) * | 1986-06-14 | 1986-07-23 | Renishaw Plc | Coordinate positioning apparatus |
| US5165534A (en) * | 1989-11-13 | 1992-11-24 | Lauren Kaufman | Packaging cases incorporating elevating mechanism for displaying contents |
| US5242670A (en) * | 1992-07-02 | 1993-09-07 | Gehringer Ronald C | Method for hydrofluoric acid digestion of silica/alumina matrix material for the production of silicon tetrafluoride, aluminum fluoride and other residual metal fluorides and oxides |
| US5901338A (en) * | 1998-06-05 | 1999-05-04 | Starmet Corporation | Method for producing uranium oxide and silicon tetrafluoride from uranium tetrafluoride, silicon, and a gaseous oxide |
| US5888468A (en) * | 1998-06-05 | 1999-03-30 | Starmet Corp. | Method for producing silicon tetrafluoride from uranium tetrafluoride |
| US5918106A (en) * | 1998-06-05 | 1999-06-29 | Starmet Corp. | Method for producing uranium oxide and a non-radioactive fluorine compound from uranium tetrafluoride and a solid oxide compound |
| US6086836A (en) * | 1999-03-29 | 2000-07-11 | Starmet Corporation | Method for producing uranium oxide from uranium oxyfluoride and silicon |
| US6096281A (en) * | 1999-03-29 | 2000-08-01 | Starmet Corporation | Method for producing uranium oxide from uranium oxyfluoride |
| US6033642A (en) * | 1999-03-29 | 2000-03-07 | Starmet Corporation | Method for producing silicon tetrafluoride from uranium oxyfluoride |
| JP3909385B2 (en) * | 2001-07-12 | 2007-04-25 | 昭和電工株式会社 | Tetrafluorosilane production method and use thereof |
| US7666379B2 (en) * | 2001-07-16 | 2010-02-23 | Voltaix, Inc. | Process and apparatus for removing Bronsted acid impurities in binary halides |
| JP4014451B2 (en) * | 2001-09-11 | 2007-11-28 | セントラル硝子株式会社 | Method for producing silicon tetrafluoride |
| TW200512159A (en) * | 2003-09-25 | 2005-04-01 | Showa Denko Kk | Method for producing tetrafluorosilane |
| US20110101273A1 (en) * | 2005-09-16 | 2011-05-05 | Robert Rewick | Process and Composition for Making Rare Earth Doped Particles and Methods of Using Them |
| KR100831060B1 (en) | 2006-12-29 | 2008-05-20 | 대일개발 주식회사 | Method for regenerating etching waste solution of semiconductor including silicon |
| WO2010025277A2 (en) * | 2008-08-28 | 2010-03-04 | Sri International | Method and system for producing fluoride gas and fluorine-doped glass or ceramics |
| MY158672A (en) * | 2008-12-17 | 2016-10-31 | Memc Electronic Materials | Processes and systems for producing silicon tetrafluoride from fluorosilicates in a fluidized bed reactor |
| RU2549415C2 (en) * | 2012-12-05 | 2015-04-27 | Открытое акционерное общество "Ведущий научно-исследовательский институт химической технологии" (ОАО "ВНИИХТ") | Method of producing silicon tetrafluoride and triuranium octoxide from uranium tetrafluoride |
| DE102013104398A1 (en) * | 2013-04-30 | 2014-10-30 | Spawnt Private S.À.R.L. | Process for the preparation of silicon tetrafluoride |
| CN114380304B (en) * | 2022-01-21 | 2023-05-30 | 云南磷化集团有限公司 | Short-process preparation method of raw material potassium fluoride for p-fluoronitrobenzene |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD67408A (en) * | ||||
| US1247165A (en) * | 1917-03-17 | 1917-11-20 | Karl F Stahl | Method of making sodium silicofluorid. |
| US2833628A (en) * | 1954-06-09 | 1958-05-06 | Grace W R & Co | Manufacture of silicon tetrafluoride |
| US2933374A (en) * | 1955-03-29 | 1960-04-19 | Gen Electric | Process of treating fluorosilanes to form monosilane |
| GB1254785A (en) * | 1968-03-28 | 1971-11-24 | Degussa | A process for the production of silicon tetrahalides |
| US3674431A (en) * | 1970-07-01 | 1972-07-04 | Cities Service Co | Generation of silicon tetrafluoride |
| US3969485A (en) * | 1971-10-28 | 1976-07-13 | Flemmert Goesta Lennart | Process for converting silicon-and-fluorine-containing waste gases into silicon dioxide and hydrogen fluoride |
| US4262409A (en) * | 1978-04-24 | 1981-04-21 | Robroy Industries | Cable connector |
| US4282196A (en) * | 1979-10-12 | 1981-08-04 | Bell Telephone Laboratories, Incorporated | Method of preparing optical fibers of silica |
-
1984
- 1984-09-05 DE DE3432678A patent/DE3432678C2/en not_active Expired
-
1985
- 1985-03-20 EP EP85103264A patent/EP0173793A3/en not_active Withdrawn
- 1985-03-25 DK DK133585A patent/DK133585A/en not_active Application Discontinuation
- 1985-03-26 FI FI851215A patent/FI75330C/en not_active IP Right Cessation
- 1985-03-26 NO NO851213A patent/NO851213L/en unknown
- 1985-03-27 US US06/716,390 patent/US4615872A/en not_active Expired - Fee Related
- 1985-03-28 KR KR1019850002064A patent/KR860002419A/en not_active Application Discontinuation
- 1985-04-04 IN IN256/CAL/85A patent/IN162367B/en unknown
- 1985-04-11 ES ES542159A patent/ES8606828A1/en not_active Expired
- 1985-04-15 DD DD85275177A patent/DD236511A5/en unknown
- 1985-05-29 CA CA000482735A patent/CA1220322A/en not_active Expired
- 1985-06-21 JP JP60134400A patent/JPS6168315A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE3432678A1 (en) | 1986-04-17 |
| FI851215A0 (en) | 1985-03-26 |
| EP0173793A3 (en) | 1989-03-22 |
| DK133585D0 (en) | 1985-03-25 |
| DE3432678C2 (en) | 1986-11-20 |
| JPS6168315A (en) | 1986-04-08 |
| FI75330C (en) | 1988-06-09 |
| EP0173793A2 (en) | 1986-03-12 |
| FI851215L (en) | 1986-03-06 |
| DK133585A (en) | 1986-03-06 |
| KR860002419A (en) | 1986-04-26 |
| FI75330B (en) | 1988-02-29 |
| ES542159A0 (en) | 1986-05-01 |
| ES8606828A1 (en) | 1986-05-01 |
| DD236511A5 (en) | 1986-06-11 |
| US4615872A (en) | 1986-10-07 |
| IN162367B (en) | 1988-05-14 |
| NO851213L (en) | 1986-03-06 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |